n.
Function: transitive verb
Date: 14th century
1 a : to make secure or fast : TIGHTEN < firm ing her grip on the racquet> ― often used with up b : to make solid or compact < firm the soil>
2 : to put into final form : SETTLE < firm a contract> < firm up plans>
3 : to give additional support to : STRENGTHEN ― usually used with up
intransitive verb
1 : to become firm : HARDEN ― often used with up
2 : to recover from a decline : IMPROVE <the market is firm ing >